The invention relates to improvements in methods of and in apparatus for manipulating folded sheets, for example, in machines for gathering sheets into brochures, books, pamphlets and like products.
European Pat. No. 0 095 603 discloses an apparatus which is designed to manipulate folded printed sheets and employs an endless gathering conveyor with a plurality of spaced-apart saddles each of which is designed to receive a succession of differently imprinted sheets, one on top of the other or others. Additional conveyors are provided to deliver discrete printed sheets for deposition onto successive saddles in different portions of the path which is defined by the gathering conveyor. Each additional conveyor comprises an endless chain or a like transporting element for a set of grippers which advance in the same direction as the saddles, at least in those regions where successive grippers are to drop printed sheets onto successive saddles of the gathering conveyor. The grippers engage the respective sheets at the fold lines between the overlapping panels of the sheets, and such sheets are opened up by a device which is installed beneath the additional conveyors and moves the panels of the sheets apart so that the released opened sheets can descend onto the adjacent saddles. The opening device employs a relatively fast belt conveyor which engages the front panels of sheets arriving at the opening station, and a somewhat slower second conveyor with tongs which engage the rear panels and whose mutual spacing is the same as that of the grippers forming part of the additional conveyors.
A drawback of the patented apparatus is that the movements of various conveyors, of their grippers and of their tongs must be synchronized at a plurality of different locations between the printing press which delivers the sheets to the additional conveyors and the saddles of the gathering conveyor. This can result in undesirable accumulations of sheets at the various transfer stations. Another drawback of the patented apparatus is that each and every change of format of the sheets necessitates prolonged and complex changes of setup with attendant substantial losses in output. All in all, the operation of the patented apparatus is rather complex and the number of stoppages due to malfunctioning of various components is rather high.
An apparatus for transporting sections of newspapers from a first conveyor to a spaced-apart second conveyor by a rotary turret-shaped intermediate conveyor is disclosed in commonly owned U.S. Pat. No. 5,110,108 granted May 5, 1992 to Hans Muller for "Sheet transporting apparatus".